The purpose of this study is to investigate the tolerability, pharmacokinetic profile of BIA 3-202 and its metabolites, and the pharmacokinetic and pharmacodynamic interaction between 4 different single doses of BIA 3-202 (50 mg, 100 mg, 200 mg and 400 mg) and a single dose of standard levodopa 100 mg/benserazide 25 mg (Madopar® 125) in adult male and female healthy volunteers.